WILLIAM H. AVERY
OCEAN THERMAL ENERGY CONVERSION
CONTRIBUTION TO THE ENERGY NEEDS OF
THE UNITED STATES
Ocean Thermal Energy Conversion (OTEC) can provide energy to the United States via direct
electric transmission from offshore U.S. island or Gulf of Mexico sites, or via production of an
energy-intensive product on an OTEC plantship sited in tropical waters . Ammonia is an
outstanding choice for the second option. Projected costs of OTEC ammonia and electricity after
1990 are competitive with projected costs from natural gas and from coal or nuclear plants,
respectively.
INTRODUCTION
OTEC is a method of converting into electrical
energy the solar energy stored by the sun in the
surface layers of the tropical oceans. The electrical
energy that can potentially be generated in that way
is many times larger than the projected total U.S.
energy needs (Table 1).
The technical details of the process have been
described previously. 1,2 A working fluid is vaporized at the temperature of the warm ocean-surface
water, expanded "through a turbine, and recondensed by cold water pumped from a depth of 3000
ft. The key features required are an efficient,
durable heat exchanger for the evaporation and
"condensation of the working fluid and a suitable
water pipe to deliver the cooling water to the condensers. Of several possible working fluids, ammonia has the most attractive thermodynamic
properties.
Two commercially attractive methods of operation of OTEC plantships are under development.
Table 1
ENERGY POTENTIALLY A VAILABLE FOR OTEC
Ocean area suitable for OTEC
plantships (~T greater than 40°F)
Estimated minimum operating
area per 325 MWe plants hip
Total OTEC power generation
capability on board
(20,000,000/650 x 325)
Total power generation on U.S.
mainland via ammonia and fuel
cells
- 20 "million mi 2
-650 mi 2
-lO,OOOGWe
-9 x lO 13 kWh/ yr
-5000GWe
-4 x 10 13 kWh/ yr
Energy Demand
U.S. total consumption (1978)
U.S. peak load (1978)
Volume I, N umber 2, 1980
2.3 X 10 12 kWh
396GWe
In the first, OTEC plants will be moored in areas
near shore where a suitable temperature difference
between surface and lower water layers is available;
power will be transmitted by underwater cable to
the utility grid on shore. In the second, plants hips
will be sited in the areas of maximum temperature
differences in the tropical oceans and will move
about slowly to remain in the warmest surface
water, which drifts with the seasons. Oceanographic data show that an annual average temperature difference of 43.0°F could be available for
OTEC by using this mode of operation. (The term
"grazing" has been used to describe the 0.5 knot
speed of the ships.) These grazing plantships are
designed to use the electric power generated on
board to make a chemical product for shipment to
U.S. ports. There this product may be used either
to replace a product now requiring petroleum fuel
or electric power for its manufacture, or it may be
used as a fuel source for electric power generation.
Because of temperature advantages and environmental trade-offs, the cost of energy delivered to
mainland U.S. sites is estimated to be nearly the
same for the grazing OTEC system as for the
moored plants in the Gulf of Mexico. If a temperature difference of 40°F is available between the
warm surface water and the cold water at depth,
about 25% of the electric energy produced will be
needed to drive the water pumps and other auxiliaries, leaving 750/0 of the gross OTEC power output to be used for other purposes. As is shown in
Fig. 1, the OTEC net power output depends
strongly on this temperature difference, dT. A
plant designed to deliver 100 MWe when operating
at a site in the Gulf of Mexico where the dT is
38°F can deliver 140 MWe with the same water
flows when operating in the ocean near the equator
where a dT of 43 OF can be found.
Figure i shows the vast region of the oceans that
is suitable for OTEC operation, i.e., where an an101
nual average LlT of 40°F exists. The area enclosed
by the 40°F contours is 20 million square miles.
Table 1 shows that this area could support 30,000
325-MWe OTEC power plants if all of the suitable
ocean area were used. About 3000 such plants
would be able to supply the projected total needs
of the United States for electric power in the year
2000 via ammonia and fuel cells if one half of the
power produced on-board were delivered to U.S.
sites via the OTEC ammonia/fuel-cell route.
AMMONIA SYNTHESIS
Pumps and au xiliaries
including clean ing
400
Tropical ocean (100%)
Puerto Rico (94%)
-Hawa
- -ii (68%)
--UJ
200
100
Warm to cold water 6. T (0 F)
Fig. 1-The estimated power delivery of a 325 MWe plant
as a function of the available temperature difference.
Numbers in parentheses indicate the power loss that
results from lowering surface water temperatures for
three off-shore locations.
A survey of chemical compounds suitable for
transporting OTEC energy to shore shows that ammonia (NH 3) is nearly ideal for this purpose. By
coincidence, ammonia is also the preferred medium
for the OTEC plant heat exchanger. It can be manufactured aboard the OTEC ship from nitrogen,
which can be extracted from the air, and hydrogen,
which is made by electrolysis of seawater.
Ammonia is formed in an equilibrium process
with little evolution of heat so that it efficiently
transforms electrical energy into storable chemical
energy. It is easily liquefied, stored, and shipped.
On land it may be stored indefinitely at ambient
temperature in pressure containers similar to those
used for liquid propane. Ammonia is already a major industrial chemical, since it is the basis for all
nitrogen fertilizer made in the United States and
for other materials such as Acrilan and nylon. Ammonia production was 18 million tons in 1978; it is
expected to increase to 25 to 28 million tons per
year by 1995. Ammonia, now made in the United
States from natural gas, consumed 630 billion ft3
of natural gas in 1978. This quantity is approximately equal to the total residential use of natural
gas in the New England states plus New York and
New Jersey. With a high priority program,
substitution of OTEC ammonia for ammonia made
from natural gas could conserve natural gas in an
amount equivalent to 300,000 bbl per day of oil by
1995 and 500,000 bbl per day by 1999.
Ammonia may be used directly as a synthetic
fuel that produces only water and nitrogen as combustion products. In this role, OTEC ammonia
would provide an attractive alternative to synthetic
fuels derived from coal, which pose problems in
mining, transportation, control of emissions, and
the long-range effects of carbon dioxide on the
global climate. At the estimated delivered cost in
Fig. 2-The available temperature differential between the surface and the 3000 ft water depth in the Atlantic,
Pacific, and Indian Oceans (DOE data).
102
Johns H opkins A PL Technical Digest
the 1990's, OTEC ammonia would compete in
price with gasoline or fuel oil at approximately $2
per gallon (1980 dollars). Although the projected
cost is higher than current estimates for synthetic
fuel from coal, the favorable environmental aspects
warrant serious consideration of ammonia as a synthetic fuel because it is easy to handle and store.
Procedures for storage and handling of ammonia
already exist because of its use in the fertilizer and
refrigeration industries.
The use of ammonia as a fuel for motor vehicles
with conventional internal combustion engines has
been demonstrated to be feasible by means of
modifications to the ignition system and installation of a pressure tank. The modifications are comparable in cost to those required to adapt a vehicle
to propane fuel. With the advent of fuel cells
adapted for use in automobiles, motor vehicles
employing ammonia fuel would have comparable
mileage efficiency to that of gasoline-powered cars
and could eliminate the pollution caused by
undesired combustion products.
Ammonia is formed by combining three parts
hydrogen and one part nitrogen under high
pressure in the presence of a catalyst. It may be
decomposed easily by application' of higher
temperature and lower pressure in the presence of
the same catalyst to provide hydrogen that is
chemically pure, except for the 25% (by volume)
fraction of inert nitrogen, and is preeminently
suitable for generation of electric power through
reaction of hydrogen and oxygen in a fuel cell.
Fuel cells convert the chemical energy of the
hydrogen and oxygen reaction into electrical energy
with an efficiency of 50 to 65070, compared to 30 to
35% attainable with gas turbine systems and about
40% maximum for steam turbines.
The most efficient fuel cells currently available
are those developed by General Electric, which
employ a solid polymer electrolyte (SPE).) SPE
cells that have practical current densities and use
hydrogen and oxygen as reactants now have a maximum demonstrated efficiency (the ratio of electrical energy output to heat of the reaction) of
65%. Some improvement is expected with further
research. However, estimates of fuel-cell efficiencies (71) range from 0.5 for state-of-the-art SPE
cells to 0.65 expected by 1985-90. The ammonial
fuel-cell cycle is shown in Fig. 3.
There is a loss of energy in using OTEC electric
power to form the ammonia that is decomposed
later to produce electric power. However, the much
larger power output of grazing OTEC plants hips
operating near the equator and the transport and·
storage advantages of ammonia compensate for the
efficiency loss, when compared with direct
transmission of electrical power to shore. Thus the
cost of delivered power is estimated to be nearly
the same for OTEC plants moored in the Gulf of
Mexico and delivering power to shore via underwater cable, as for grazing OTEC ammonia plantVolume I, Number 2,1980
Electric
Air
OTEC
ammonia ~ Storage t--~~rv-..rvt-----..J
Fig. 3-Schematic diagram of the use of ammonia as the
power source in a fuel cell. CTEC-synthesized ammonia is
decomposed in a converter. The reaction products
(nitrogen and hydrogen) are partially used as the fuel in
an oxygen-enriched fuel cell. Ten percent of the hydrogen
is burned in air to supply the heat required to decompose
ammonia.
ships delivering to' shore ammonia to be decomposed and used in fuel cells to produce electric
power. The latter mode of operation allows OTEC
to draw on the vast tropical ocean area as an
energy reservoir and to supply a source of electric
power anywhere in the United States. Because fuel
cells are quiet and efficient even in small sizes,
power generation by fuel cells can be adapted for
use by factories or communities where large nuclear
or coal plant installations are not feasible.
Figure 4 shows a conceptual design of a 100MWe OTEC ammonia plantship made up of twenty 5-MWe power modules. It is 450 ft long, 180 ft
wide, and 60 ft deep and is made of reinforced
concrete.
PROJECTED COSTS
During the past two years, major effort in the
Department of Energy (DOE) OTEC program has
been devoted to definition of baseline engineering
designs of 40-MWe pilot/demonstration plants that
will provide a firm basis for industry proposals,
with construction to begin in 1984 or early 1985.
The purpose of the pilot plants is to provide accurate data on component performance and cost
for follow-on construction of moored and grazing
commercial . plants of 100- to 400-MWe busbar
power. Under DOE support, a two-year engineering evaluation effort has been conducted by APL
and representatives of the shipbuilding and marine
construction industries to define a baseline barge
configuration for the 40-MWe pilot plant. 4 Other
configurations have been investigated by other
organizations but the estimated costs are appreciably higher. The APL design is similar to that
shown in Fig. 4, but is scaled down to 40 MWe.
The pilot plant configuration is shown in Fig. 5.
The barge platform is made of post-tensioned concrete, is 140 ft wide and 444 ft long, and has an
operating draft of 65 ft. The launching draft is 33
ft (without the cold-water pipe), which will allow
construction in existing U.S. shipyards. The coldwater pipe is 30 ft in diameter and is made of posttensioned lightweight concrete in 50 ft sections
joined by flexible connections. The concrete density
is 80 to 85 Ib/ft). The low submerged weight
103
Fig. 4-APL concept of a 100·
MWe plantship, for siting in tropical oceans, that consists of
twenty 5-MWe power modules.
Cold water is supplied from a
centrally mounted pipe, extending down 3000 ft into the ocean.
Warm surface water flows by
gravity through the heat exchanger compartments. Housing
is for demisters, electrolysis
cells, ammonia pumps and turbines, and generators.
Fig. 5-40 MWe pilot plantship configuration.
104
(about 20 Ib/ ft 3) of the pipe and its sectional construction facilitate deployment and ensure that
dynamic loads under 100-year storm conditions will
be well below safe limits for post-tensioned concrete. 4 A fiberglass-reinforced plastic cold-water
pipe is an alternative. 5
Figure 6 shows the estimated capital costs of the
pilot plants and the expected commercial OTEC
plantships for moored and grazing options (as projected from work in progress). Costs for the 40MWe pilot plants are based on preliminary
engineering drawings and on industrial estimates of
the costs of the platform cold-water pipe and of
the folded-tube aluminum heat exchanger. The heat
exchanger estimates were made by the Trane Co.,
which built the full-scale section tested at the
Argonne National Laboratory of DOE. Quotations
were obtained from vendors for the pumps, propulsion equipment, control systems, ammonia plant,
and auxiliary equipment. The cost differences
among the pilot plants for different sites reflect the
effects of differences in AT and in environmental
Johns Hopkins A PL Technical Digest
10000
_
9000
Atlantic-1 grazing
Puerto Rico
Hawa ii
8 100
8000
7870
Gulf of Mexico
7630
7000
6230
~ 6000
.E
(See Note 1)
OJ
~ 5000
(See Note 2)
0"
ex)
en
::. 4000
w
3000
2000
1000
0
Mi nimum power
___---'-"-_ _ _I~
266
189
232
192
217
98
I~I
I~ I
Eighth commercial plant
Nuclear
I
~
Pilot/ demo plants
First commerc ial plant
I
Coal
Note 1 Construction after island installation (s}
2 For 400 MW plant, range is 2810 to 2160 $/ KW e for average power, 5400 to 4150 $/ KW e f or minimum .boT.
Fig. 6-Estimated total capital costs of OTEC power plants in four different locations and at various stages of
commercial building cycles compared to nuclear and coal plants. Numbers provide ranges of costs. (Costs are expressed in 1980 dollars at the busbar.)
rigor. Costs of mooring equipment at Puerto Rico
and Hawaii are based on preliminary industry
estimates. Costs for power conversion and
transmission from moored plants at Puerto Rico,
Hawaii, and the Gulf of Mexico are based on current DOE-supported work. Estimates are based on
data of Winer and Nicol 6 and others.
The data in Figs.~ 6 and 7 are presented in a format similar to tha't used by the Nuclear Regulatory
Commission (NRC) to show a range of costs reflecting uncertainty in the estimates. 7 The range shown
for OTEC options is taken to be from 0 to + 30ltJo
of the nominal values based on the projected cost.
The 30ltJo range provides an allowance for contingencies and profit on capital equipment not
covered by quoted costs as well as for uncertainties
in the design estimates for moored and grazing
barge configurations. This is approximately twice
the uncertainty assigned by the NRC to their
estimates. It will be recognized that projections of
future costs are highly uncertain until full-scale
systems have been constructed. Nevertheless, such
estimates must be attempted to distinguish the good
options from the economically impractical ones.
The author ' assumes sole responsibility for these
estimates.
Cost reductions in dollars per kilowatt (Fig. 6)
for the first commercial plants relative to the pilot
plants result from scale-up of the platform, from
colocated aluminum tubing manufacture and
Volume J, Number 2, J980
establishment of automatic assembly line production procedures for the heat exchanger modules,
from more efficient arrangement of the equipment
than that used for convenient access in the pilot
plant tests, from scale-up of the turbine generators
and support equipment, and from design improvements that will be indicated by pilot plant experience. Further cost reductions shown for the
eighth plantship are expected to result primarily
from volume production and improved manufacturing procedures. Learning curve factors based on
shipyard experience indicate that the cost of the
second commercial platform will be 80ltJo of that of
the first, after which a learning curve slope of 0.93
is used for succeeding platforms. 8 Learning curve
slopes of 0.95 and 0.90 are assumed for the heat
exchangers and the rotating equipment, respectively, and 0.93 for the ammonia plant.
The capital costs quoted for the grazing plantships are based on the preliminary engineering
design of the grazing configuration planned for
operation 200 or more miles off Brazil or Central
America, where an annual average LlT of 43.0°F
will be available. Higher costs compared to the
grazing plants hip are estimated for the moored
plantship off Puerto Rico because of the need for
heavier platform and cold-water pipe construction
to meet the more severe environmental stresses, and
because the lower LlT causes diminished power output. Estimated costs for Hawaii are adjusted for
105
Fuel cost
Ammonia fuel
II
0 +M
Capital cost
220r-------------------------------------~
Centra l power
stations
throughout
U.S.
200
180
160
Gulf of
Mexico *
_140
~
o
en
~
120
<{]i :
' \;::::::-
QJ
..c
3: 100
.'\;;: Ce ll effi ciency
~
50%
65%
40
20
O~--~----~--~----~--~--L----LL-----J
I~ I ----I
OTEC moored underwater OTEC ammonia
cable power t ransmi ssion
f uel cel l
* Comp lete system not def ined
power
I "'-v-' I I"'-v-' I
Coal
power
plant
Nuc lear
power
plant
monia that is transported to U.S. sites and used
there to provide electric power via fuel cells. For
the plants moored where several tropical storms
may occur each year, 330 days of operation per
year are assumed. Power conversion and transmission efficiency of 97OJo are estimated for the Puerto
Rico and Hawaii installations and 95% for the
Gulf of Mexico sites.
For the grazing plantships that operate in the
Atlantic near the equator where tropical storms do
not occur (the doldrums), 345 operating days per
year are pr()jected, leading to an annual ammonia
output of 380,000 tons per year for a 325-MWe
(net) plantship (1.17 tons / kWe). The fuel-cell costs
are shown in Table 2. Costs for production and
delivery of OTEC ammonia to U.S. sites are shown
in Table 3. This table provides the basis for the
fuel cost shown for the fuel-cell installation in Fig.
7. A comparison of projected costs of OTEC ammonia versus ammonia made from fossil fuel
stocks indicates that OTEC ammonia after 1985
will be lower in cost. JO
The costs listed in Fig. 8 are derived by using the
detailed procedures developed by NRC and DOE,
which are explained in Ref. 7. Further information
on recent costs has been provided by Roddis. II In
accord with that reference and to allow direct comparison of OTEC estimates with those presented in
Fig. 7-Estimated busbar price of power (mills/kWh) to
U.S. sites for three OTEC plants at near·land locations
(Puerto Rico, Hawaii, Gulf of Mexico) with direct power
transmission to land, for OTEC·produced ammonia powering land-based fuel cell plants, and for coal or nuclear
fuel power stations. (Prices are in 1990 dollars at an 8%
inflation rate, and with a 10% discount for coal and
nuclear fuel.)
lower dT compared with Puerto Rico. Costs for
the Gulf of Mexico allow for the lower dT and the
added cost of the long underwater power transmission system, for which the engineering requirements
have not been defined. The· upper boundaries for
the Gulf of Mexico plants in Fig. 6 are uncertain.
Fuel-cell costs are based on General Electric
estimates derived from an ongoing program to
scale up their present SPE fuel cell to 5-MWe utility use. Use of pure hydrogen derived from ammonia will simplify fuel-cell construction and make
the SPE fuel-cell system significantly lower in cost
than phosphoric acid fuel cells. The latter type is
designed to be tolerant of impurities in hydrogen
derived from coal or petroleum fuels. 9 Because
such hydrogen contains sulfur and carbon monoxide contaminants, higher temperature operation
and less efficient (and much more costly) fuel-cell
systems are required.
The projected costs of delivered electric power
are shown in Fig. 7. The data are presented for
moored plantships near the shores of Puerto Rico
and Hawaii and 150 miles offshore in the Gulf of
Mexico, and for grazing plantships producing am106
Table 2
ESTIMATED OTEC AMMONIA
FUEL-CELL SYSTEM COST
$/ kWe OUTPUT POWER (1980 dollars)
Hydrogen-Oxygen
Fuel Cell
71=0.50 71=0.65
Ammonia converter
Fuel cell and power conditioning
Oxygen separation plant
Storage
Total $/ kWe
$ 90
200
100
20
$ 70
400
100
20
$410
$590
0.100 -O. 124
1. 707
1.313
0.073
0.059
Ammonia cost $/ lb
kWh/ lb
Ammonia cost $/ kWh
Table 3
ESTIMATED CASH COSTS OF
OTEC AMMONIA DELIVERED (1980 dollars)
Plantship investment,
eighth plantship ($/ kWe)
Annual ammonia production (tons/ kWe)
$1200
1.17
Cost per ton
Ammonia
Shipping
Delivered
$184-$232
$16
$200-$248
J ohns H opkins A PL Technical Digesl
Ref. 11 for coal and nuclear power plants, the
following assumptions are made:
• 20OJo return to the owner/operator on invested
capital;
• 9OJo interest on debt;
• Title XI financing by the Maritime Administration, which provides loan guarantees
for 87.5OJo of the plant investment;
• Thirty-year plant life;
• Thirty-year sum of years' digits sinking fund;
• Federal income tax of 48OJo with 10OJo income
tax credit in the first year;
• Insurance ofO.50J0 on plant investment;
• IOJo of plant investment per year for interim
replacements versus 0.65OJo used for coal and
nuclear estimates (allows for replacement of
the aluminum heat exchanger after 15 years);
• No local and federal property taxes; and
• 0.35OJo annual taxes on other items.
The comparison indicates that both moored and
grazing OTEC plants will deliver power in 1990 to
U.S. mainland sites at prices competitive with projected coal prices, and power from moored plants
in Puerto Rico and Hawaii will be even lower than
projected nuclear costs.
COMMERCIALIZATION
Along with technical development of OTEC,
studies and investigations have been conducted to
determine what institutional, legal, and commercial
barriers must be overcome to permit OTEC to
become a major new energy industry. The studies
have shown that legal and environmental barriers
to OTEC operation are minimal. Until recently,
however, industry interest has been low. Developments within the past year have modified earlier
negative opinions, and support is now emerging
both from the electric utilities and from ammonia
producers for early demonstration of OTEC
capabilities.
Projected costs of delivered power from the first
moored pilot! demonstration OTEC plants at sites a
few kilometers offshore in Puerto Rico and Hawaii
are low enough to make OTEC power a profitable
venture if about half of the capital costs of these
small sized plants can be supplied from federal
funds. The projected cost of power from imported
oil, the only present source of power in those
islands, makes OTEC power particularly attractive
for those sites. To facilitate early commercial plant
development, the Commonwealth of Puerto Rico
and the Puerto Rico Electric Power Authority (with
some local industry support) proposed in 1979
sharing part of the costs of developing a moored
40-MWe pilot plant, if - after the initial shakedown - DOE would assign the power produced by
the pilot plant to the Puerto Rico utility. A similar
proposal was explored by the State of Hawaii. A
Volume 1, Number 2,1980
group of ammonia producers submitted to DOE a
proposal to provide 40 million dollars in cost sharing for the construction of a 40-MWe pilot ammonia plants hip if the 125-ton per day ammonia
output would be assigned to them for sale.
However, none of these unsolicited proposals was
accepted by DOE, which favors use of a competitive bidding procedure and a more deliberate
schedule for selecting OTEC programs to support.
The proposals to share funding of · the pilot
plants provide encouraging evidence of industry
commitment to rapid commercialization of OTEC
after the expected performance of the pilot plant is
successfully demonstrated.
CONCLUSION
OTEC plants hips thflt produce ammonia can
supply electric power via hydrogen fuel cells to all
regions of the United States and can conserve
natural gas now used as a feedstock for ammoniabased fertilizers and chemicals. Ammonia also has
an attractive potential as a synthetic fuel alternative
to synthetic fuels from coal. Moored OTEC plants
sited near Puerto Rico or Hawaii, or offshore in
the Gulf of Mexico, can supply electric power directly to utility grids onshore via underwater
cables. Projected costs of OTEC ammonia and
electrical energy after 1990 are comparable with
those projected for conventional plants based on
fossil fuel or nuclear p·ower. Since OTEC energy
will be inexhaustible, economical, and environmentally benign, OTEC deserves high priority among
the Nation's energy programs.
REFERENCES and NOTES
IG . L. Dugger, E. J. Francis, and W. H. Avery, " Technical and
Economic Feasibilit y of Ocean Thermal Energy Conversion ," Sharing
the Sun (Proc. International Solar Energy Society Conf. , 1978). Also
in Energy 20, pp. 259-274 (1978).
2G. L. Dugger (ed .), Ocean Thermal Energy for the 80's , Proc. 6th
Ocean Thermal Energ y Con version (OTEC) Conf. , DOE
CONF-790631 ,·Vols . I and 2 (1979).
3L. J . Nuttal, " Status of Solid Polymer Electrolyte Technology ," in
Ref. 2, Vol. I, p. 10-7.
4 J. F. George, D. Richards, and L. L. Perini, "A Baseline Design of an
OTEC Pilot Plantship ," AP LI JHU SR 78-3 (1979).
5W . G . Sherwood and J . P. Walsh , "OTEC Ocean Engineering Progress Report ," in Ref. 2, Vol. I, p. 5-L
6B . M. Winer and J. Nicol, " Electrical Energy Transmission for OTEC
Power Plants," in Proc. 4th OTEC Con/., p. III-26 (1977).
7Nuclear Regulatory Commission, " Total Generating Costs - Coal and
Nuclear Plants, NUREG-0248 , Table 4-3 (1979) .
8Each time the number of units doubles, the cost is reduced by this factor. Thus the second unit costs 0.93 times the cost of the fir st, the
fourth costs 0.93 times the second, the eighth costs 0.93 times the
fourth, and so on .
9A . P. Fickett, "EPRI Fuel Cell Program Overview," Proc. National
Fuel Cell Seminar, p. 5 (1979) .
IOE. J . Francis, "Investment in Commercial Development of OTEC
Plant Ships, " Dept. of Commerce (MARAD) (Dec. 1977).
II L. Roddis, private communication: "Present capital costs are in the
range $1000 to $1200 per kW for both coal and nuclear. Nuclear fuel
cost is presently $38 to $40 per lb ."
107